Wozniacki, the current world No. 10 and No. 6 seed in Brisbane, most recently won the indoor Luxembourg Open, beating Sabine Lisicki and Annika Beck in the process. Her last outdoor hard-court appearance came in Beijing, where she lost in straight sets to Serena Williams in the quarters.

The severity of the 23-year-old's injury is currently unknown, and it will be interesting to see if she's fit for the Apia International in Sydney and more importantly the Australian Open in Melbourne.

Wozniacki struggled in 2013, reaching just two finals (with one win) and failing to make the quarters at any of the Grand Slams for the first time since 2008.

She was scheduled to play Dominika Cibulkova in the first round at Brisbane. Cibulkova will now take on Kimiko Date-Krumm or Olivia Rogowska in the second round.